Electrolytic cells are used in a variety of applications to generate oxidants for use in disinfection. Electrolytic technologies have been developed to produce mixed-oxidants and sodium hypochlorite solutions from a sodium chloride brine solution. U.S. Pat. No. 4,761,208 by Gram, et al. describes an electrolytic method and cell for sterilizing water. These electrolytic cells typically have a source water feed stream and a brine feed stream. The feed water can typically be softened to remove carbonate from the water stream, and softened water can also be used to generate the brine solution. However, salt for making brine often contains calcium as a contaminant in the salt. Due to the concentration of the brine, the brine can not be softened using ion exchange resin.
Operating conditions within the cell are ideal for the formation of scale deposits on electrode plates. For instance, calcium carbonate scale can build up on the cathode electrode of a chlorine producing electrolytic brine cell. Carbonate scale can electrically blind the cathode causing localized current density increases in the opposing dimensionally stable anode (DSA), which can cause passivation failure of the DSA coating. This failure mode can cause rapid destruction of the electrolytic cell.
By measuring the formation of carbonate in the oxidant fluid stream exiting the electrolytic cell, the electrolytic cell operation can be alarmed or terminated. This will allow maintenance to be timely performed on the electrolytic cell to repair the effects of the carbonate scale before destruction of the electrolytic cell occurs. The present invention can also be used to detect carbonate formation in any aqueous fluid where carbonate formation is considered a contaminant in the system. Examples include boiler water systems, distilling systems, ion exchange water softening to indicate that resin regeneration is required, membrane softening systems, dialysis systems, commercial sodium hypochlorite pumping and piping systems, and any other applications where a contaminant attracted to a material in a high pH environment can be detected.